No Link Between Vaccines, Autism: WHO

A new analysis from the World Health Organization’s (WHO) Global Advisory Committee on Vaccine Safety (GACVS) has reaffirmed that no causal link exists between vaccines and autism spectrum disorders (ASD), reinforcing long-standing scientific consensus on the safety of routine immunization.

GACVS, an expert group formed in 1999 to provide independent guidance on vaccine safety, reviewed evidence during its Nov. 27, 2025, meeting. The assessment focused on two areas often cited in public debate: thiomersal-containing vaccines and aluminum-adjuvanted vaccines. The Committee examined 31 primary research studies published from 2010 to August 2025, covering multiple countries and vaccine types administered during childhood and pregnancy.

The analysis found no association between thiomersal, a preservative used in some vaccines, and ASD. The Committee also reviewed research on aluminum adjuvants, including studies conducted between 1999 and March 2023 and a recent large cohort study based on Denmark’s nationwide registry of children born from 1997 to 2018. The findings showed no link between exposure to trace amounts of aluminum in vaccines and ASD.

The conclusions align with previous assessments issued in 2002, 2004, and 2012, which also found no evidence that vaccines cause autism. WHO emphasized that national health authorities should continue grounding vaccine policies in scientific evidence, noting that global immunization efforts have saved an estimated 154 million lives over the past five decades.

As countries work to maintain or restore vaccination coverage, WHO highlighted the importance of sustained public confidence. The organization stated that ongoing monitoring, transparent communication, and reliance on high-quality data remain central to immunization strategies worldwide.

“Vaccines save lives, allowing individuals, families, communities, economies, and nations to flourish,” says Tedros Adhanom, Director General, WHO. 

Vaccination has long been a cornerstone of public health policy, protecting individuals from life-threatening diseases and serving as a recognized human and social right, reports Mexico’s Ministry of Health. According to WHO, vaccines can prevent over 30 infections, enabling people of all ages to live longer and healthier lives. Yet, recent data show that coverage gaps remain, threatening to reverse years of progress.

Ensuring widespread protection requires coordinated action by governments, healthcare workers, civil society, international organizations, and individuals to strengthen immunization programs. In Mexico, hesitancy around certain vaccines, such as those for COVID-19, influenza, and HPV, continues to pose an obstacle, says Rodrigo Romero, Coordinator, Mexican Association of Vaccinology. This trend is also evident in other countries, where even health authorities are making statements or recommendations that undermine vaccines or raise doubts about their effectiveness

For example, the US Centers for Disease Control (CDC) has updated its website to state that a link between vaccines and autism cannot be ruled out, reversing its previous position despite extensive research showing no connection. Also, in early December, the US Advisory Committee on Immunization Practices (ACIP) voted in favor of removing the universal hepatitis B vaccine recommendation for infants under two months old. The shift aligns with Robert F. Kennedy Jr.’s, US Minister of Health, long-standing promotion of the debunked claim. 

Rebuilding public trust remains central to expanding coverage. Confidence in vaccines depends not only on their proven safety and effectiveness but also on the ability of institutions to deliver them competently and transparently. Authorities face the task of countering misinformation, addressing community-specific concerns, and ensuring fair distribution across regions.

“Vaccine hesitancy remains a complex problem which is determined by various factors such as individual motivation, insufficient knowledge, lack of confidence in the benefits of vaccination, overconfidence in one’s ability to avoid the disease, anxiety about vaccines, and fear of side effects to name a few,” says Oxford Policy Management.